An accelerator pedal, a brake pedal, a clutch pedal or the like may be provided with an operation amount sensor for detecting an operation amount of the pedal. The detection value detected by the operation amount sensor is converted to an operation amount of the pedal by a computing device based on a difference between the detection value and a start point detection value, which is a detection value when the pedal is at a start point position.
The start point detection value may be set to a uniform value prior to assembly of the pedal and the operation amount sensor at the factory, or may be set based on the detection value detected by the operation amount sensor after the assembly. Though the start point detection value has been set at the time of shipping from the factory, the start point detection value may be shifted due to deterioration of the pedal and the sensor over time (such as wear or positional displacement) as the pedal operation is performed repeatedly during use. For this reason, there is a computing device configured to update the start point detection value at appropriate times based on the detection value after setting of the start point detection value.
As a minimum value (start point detection value) updating method for an accelerator pedal device for updating the start point detection value, a method is known in which when the output value from an accelerator pedal sensor has shown a value less than a currently stored minimum value by a predetermined value or more within a predetermined variation range for a certain period of time continuously or has shown a value greater than the currently stored minimum value by a predetermined value or more within a predetermined variation range for a certain period of time continuously, the minimum value is updated based on the sensor output value at that time (Patent Document 1).